Cressa (Cressa truxillensis Choisy), [Fig. 88], perhaps identical with C. cretica auct.
Saltgrass (Distichlis spicata), [Fig. 89].
Tussock-grass (Sporobolus airoides, Torr.); [Fig. 82].
(“Bunch grass” of New Mexico).
The three sets of Tussock-grass soil which have been analyzed show that the total amount of all salts present is in no case less than 49,000 pounds per acre, to a depth of four feet; and that it sometimes reaches the extraordinarily high figure of 499,000 pounds. Of these amounts the neutral salts (Glauber’s salt and common salt) are usually in the heaviest proportion (Glauber’s salt, 19,600 to 323,000 pounds per acre; common salt, 3,500 to 172,800); the corrosive salsoda varying from 3,000 to 44,000 pounds.—Tussock-grass apparently cannot persist in ground which is periodically flooded. It is of special importance because it is an acceptable forage for stock.
Tussock-grass is a prevalent alkali-indicator in the hot, arid portions of the interior, from the upper San Joaquin Valley, the Mojave desert, and southward; also through southern Nevada and Utah as far east as Kansas and Nebraska. In the San Joaquin Valley it has not been found farther north than the Tulare plains, although east of Reno it occurs near Reno. Coville observes that in the Death Valley region “it is confined principally to altitudes below 1,000 meters” (3,280 feet). Hillman, however, reports it from near Reno, Nevada, at an altitude which cannot be much less than 4,500 feet.
Fig. 82.—Tussock-Grass—Sporobolus airoides Torr.
The tussocks formed by this grass, which are unfortunately not shown in the figure, sometimes appear as veritable little grass trees, and when denuded by the browsing of cattle seem like trunks 18 and 20 inches high. It is therefore very easily recognized; but it should be noted that in view of the extraordinary range of its tolerance, shown above, its scattered occurrence does not necessarily indicate irreclaimable land.
Bushy samphire.
(Allenrolfea occidentalis [Wats.] G. Ktze.) Fig. 83..